Does the Mac need Vulkan? It's not as if it was widely used. Games will still be coded with directX or console API. Vulkan will be as irrelevant as OpenGL for games.
So Apple is better off using Metal, an API they can control and which does the job.
Metal has more than 148 000 apps using it directly (mostly games I suppose) and 1.7M using it through higher level framework. Compared to the few dozens apps using Vulkan.

Not really natively, as the support works via a Vulkan to Metal translation library (MoltenVK – which I seem to have underestimated in the past), but together with a newly released SDK, that was enough for the Khronos group to make the support official. Valve also has already tested the Vulkan version of Dota 2 under macOS, and it's significantly faster than the OpenGL version.

"We do what we must, because we can."
"Gaming on a Mac is like women on the internet." — "Highly common and totally awesome?"

vulkan to metal translation layer sounds nice but is anyone using vulkan over directX 12?

The usual porting houses feral and aspyr are already adept at natively porting directX to metal and the major engines like Unreal4 already support metal so I’m not sure who this is for unless there is more uptake in vulkan than I realized.

Not really natively, as the support works via a Vulkan to Metal translation library (MoltenVK – which I seem to have underestimated in the past), but together with a newly released SDK, that was enough for the Khronos group to make the support official. Valve also has already tested the Vulkan version of Dota 2 under macOS, and it's significantly faster than the OpenGL version.

So Dota 2 runs faster with Vulkan code translated to Metal than with openGL code? It'd go even faster with native Metal code.

Seriously, I don't see anyone beside Valve using this translation layer for macOS games, but I'd be interested in hearing Feral's take on this.
Most games will use DX anyway. And for the few that use Vulkan only (I can't think of any), this translation layer will not influence much in the decision to port a game to Mac. There are already many games using UE4/Unity5 and which are not ported to Mac or Linux.
That is, unless a Windows game could run on macOS without modification, but I doubt that's the case.

So Dota 2 runs faster with Vulkan code translated to Metal than with openGL code? It'd go even faster with native Metal code.
Seriously, I don't see anyone beside Valve using this translation layer for macOS games, but I'd be interested in hearing Feral's take on this.

I could see it being useful for code weavers if the uptake was better. But according to wikipedia there's only a couple dozen vulkan games anyway. I think the best case scenario is more developers use vulkan now that it can be relatively portable to a platform full of hungry paying customers.

So Dota 2 runs faster with Vulkan code translated to Metal than with openGL code? It'd go even faster with native Metal code.

Seriously, I don't see anyone beside Valve using this translation layer for macOS games, but I'd be interested in hearing Feral's take on this.

Brad Oliver had a mini tweetstorm about it. The tldr is that it doesn't support tesselation and it doesn't matter for Unreal or Unity games. Really only useful for indies who use their own engine with Vulkan.

vulkan to metal translation layer sounds nice but is anyone using vulkan over directX 12?

id Software, Egosoft (the X series games), and apparently CIG (Star Citizen). Although probably the only one of these three were a Mac version is at least somewhat likely would be Egosoft.

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The usual porting houses feral and aspyr are already adept at natively porting directX to metal and the major engines like Unreal4 already support metal so I’m not sure who this is for unless there is more uptake in vulkan than I realized.

I'd guess it's primarily targeted at developers who want to develop cross-platform titles and who do not use a ready-made engine, like Croteam (Serious Sam, The Talos Principle), Flying Wild Hog (Shadow Warrior 2013), or 4A Games (the Metro series).

I mean, Metal is quite fine and dandy, but having to support some weird, proprietary graphics API that only works on a system with a relatively tiny market share is not necessarily a enticing outlook for small to medium sized developers. Having at least a feasible translation layer for a cross-platform graphics API would increase the likelihood of Mac ports of their games by quite a degree.

In addition as you said, Wine/CrossOver could also profit from being able to support Vulkan.

"We do what we must, because we can."
"Gaming on a Mac is like women on the internet." — "Highly common and totally awesome?"

The usual porting houses feral and aspyr are already adept at natively porting directX to metal and the major engines like Unreal4 already support metal so I’m not sure who this is for unless there is more uptake in vulkan than I realized.

I don't think this translation layer is adequate for something as complex as CryEngine. As mentioned above, MoltenVK doesn't support tessellation.
And performance won't be stellar. I'm taking the Dota 2 numbers with a gain of salt. I suspect there was some special tuning for Source 2, since Valve is close to LunarG and those who did MoltenVK, and they basically made Vulkan on their own (based on AMD's Mantle). If Valve spent as much effort making a Metal version of Source 2, performance would be much higher.

Vulkan on the PC is really going nowhere fast (this long since release and I think only four or five things support it, with nothing exclusively), so I would assumedly the real benefits of this are more likely to be felt by cross-platform developers currently working with OpenGL code on macOS and wanting to move to something of higher performance without taking on the burden of supporting Vulkan/DX12 on PC and Metal on Mac.

And performance won't be stellar. I'm taking the Dota 2 numbers with a gain of salt. I suspect there was some special tuning for Source 2, since Valve is close to LunarG and those who did MoltenVK, and they basically made Vulkan on their own (based on AMD's Mantle). If Valve spent as much effort making a Metal version of Source 2, performance would be much higher.

Probably, yes. I would also be interested in seeing some direct comparisons to DirectX and Windows Vulkan on the same hardware. But honestly, anything that is an improvement over Apple's crappy OpenGL is a step forward.

Anyway, Unreal Engine Mac programmer marksatt over at Macrumors is also not too optimistic:

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Specifically MoltenVK has a list of limitations that make it sufficient for porting mobile Vulkan games and games with a primarily D3D9-era rendering engine, but probably inadequate for most modern D3D11+ game engines.

…which is pretty much the same what I thought of MoltenVK before the Khronos group made it part of their official efforts.

"We do what we must, because we can."
"Gaming on a Mac is like women on the internet." — "Highly common and totally awesome?"

Vulkan on the PC is really going nowhere fast (this long since release and I think only four or five things support it, with nothing exclusively), so I would assumedly the real benefits of this are more likely to be felt by cross-platform developers currently working with OpenGL code on macOS and wanting to move to something of higher performance without taking on the burden of supporting Vulkan/DX12 on PC and Metal on Mac.

Big Mac developers have little use for it.

Correct. The limitations in MoltenVK need to worked on before it is really valuable for this but in those circumstances it may be useful. Feral, Aspyr, ourselves at Epic, Unity and so on don't really need it as we already have our Metal backends and aren't going to want to sacrifice performance in another intermediate layer.

So, gentlemen, given that Metal2 has been out for a bit and now there are Metal "backends", since I know next to nothing about programming, how would you rate the current state of (and future) of Mac gaming?